Why are the arguments supplied for the command run through ssh interpreted by shell before they are passed to the command on the server side?

[Thorsten Glaser]

On Sat, 11 Jan 2020, Yuri wrote:

> It's not obvious why does it have to be this way. ssh sends the command as an
> array of strings. The first string is the command, and the subsequent strings

It doesn’t.

This works:

  94 ssh root@$hostbase "
  95         PS4='(${hostbase%%.*})++++ '
  96         set -ex
  97         psql -U veraweb -h 127.0.0.1 veraweb
  98         rm -rf /var/lib/tomcat$tomcat/webapps/veraweb
  99         rm -rf /var/lib/tomcat$tomcat/webapps/vwor
 100     " <core/src/main/files/upgrade.sql

Here, $hostbase and $tomcat are expanded locally. Full code:
https://evolvis.org/plugins/scmgit/cgi-bin/gitweb.cgi?p=veraweb/veraweb.git;a=blob;f=upload.sh;h=b8b0cf92ad36dbc929afd86effe44d9bec888344;hb=HEAD

If you wish for no local expansion, quote locally, such as:

ssh -l luser remotehost '
	command1
	command2
	…
'

Quote any ‘'’ inside as “'\''”, that’s it. (Easily done, for
example in AT&T ksh93/GNU bash/mksh: ${cmd//\'/\'\\\'\'})

bye,
//mirabilos
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